Automatic wing lift varying device for aircraft



P. E. MERCIER AU'I'OIA'I'IC WING LIFT VARYING DEVICE FOR AIRCRAFT June 9, 1942.

Filed April 7, 1937 8 Sheets-Sheet 1 INVENTOR:

RNESTMERCIER PIERREE m mmafi AlTORNEYS June 9, 1942.

P. E. MERCIER AUTOMATIC WING LIFT VARYING DEVICE FOR AIRCRAFT B Sheets-Sheet 2 Filed April 7, 1937 W WI m mm m TE N N R E 0 T T Fawn M v J June 9, 1942. P. E. MERCIER AUTOHATICWfNG LIFT VARYING DEVICE FOR AIRCRAFT Filed April '7, 1937 8 Sheets-Sheet 3 I NVENTOR PIERRE ERNEST M ERCIER BY ,QZAQAZ AT TORNEYS June 9, 1942.

P. E. MERCIER AUTOHATIG WING LIFT VARYING DEVICE FOR AIRCRAFT Filed April 7, 1937 8 Sheets-Sheet 4 INVENTOR= PIERRE ERNEST MERCIER ,ilz 4% AT TORN 5Y5 June 9, 1942. P. E. MERCIER AUTOMATIC WING LIFT VARYING DEVICE FOR AIRCRAFT Filed April '7, 1957 8 Sheets-Sheet 5 INVENTOR PIERRE ERNEST M5120? BYiW QZZLW I ATTORNEYS P. E. MERCIER 2,286,150

Filed April '7, 1937 8 Sheets-Sheet 6 June 9, 1942.

JTOMATIC WING LIFT VARYING DEVICE FOR AIRCRAFT I NVE NTOR: PIERRE ERNEGT MERCIER BY m AT TORNEYS June 9, 1942. P. E. MERCIER AUTOMATIC WING LIFT VARYING DEVICE FOR AIRCRAFT Fiied April 7, 1957 8 Sheets-Sheet '7 mm +5 E N fi wm m w 1% A R 5% June 9, 1942. p, MERGER 2,286,150

AUTOMATIC WING LIFT VARYING DEVICE FOR AIRCRAFT Filed April 7, 1937 8 Sheets-Sheet 8 NVENTOR= PIERRE ERNEST MERCIER A'ILTORNEYS Patented 9, 1942 w'rowmc wmaur'r vsamo nnvrca ron AIRCRAFT Pierre Ernest Mercler, Paris, France Application 7, 1937, Serial N0. 135,441

April 10, 1936 Thisinvention relates to an improved; device for limiting the eflort necessary to overcome the aerodynamic forces on i-air'craft in flight.

- Aircraft, in which the support when flying-depends on the air speed thereof, when traveling at high speeds are subject to sudden variations of the aerodynamic forces which support them under the effect of atmospheric currents such as gusts ofair'or of a change of incidence caused by the pilot straightening out the longitudinal trim of the aircraft.

sence of the corresponding deflection of the said- The main object of the present invention is wings of the aircraft and adapted to be deflected upward or downward on each side of a mean position.

' 2. Of' a servo-motor having for its object to vary this deflection of the flap in as short a' time as possible. 1

3. Of a member controlling the servo-motor and herein termed the pilot member," the positions of which are a function of both the deflection of the flap and the deformation of the wing caused by the aerodynamical forces exerted thereon in such manner that within certain limits fixed in advance a; particular position of the flap in a state of equilibrium will correspond to each degree of deformation of the wing, the said correspondence depending to a varied degree upon the speed of deformation of the wing.

A particular embodiment of the pilot member referred to in its relations to the deformations of v the wing includes an element suillciently rigid with respect to the forces which it has to sustain that its length may be considered as invariable relatively to the structure of the wing, said element being located interiorlyof the wing in the direction ofthe length orw'idth thereof in its thickest portion and close to its surface, while one of the extremities of said element which may be termed the comparison element, is fixed rigidly at one point of the wing structure close to its surface. The other extremity of said element has its point of support located on the same control member of the servo-motor and is also connected to the wing structure close to the same surface in such manner that every elastic deformation of said wing structure in the form of an extension or contraction permitting flexing deformations, will produce a displacement of said control member of the servo-motor in the ab- The invention will be better understood byreference to. the .annexed drawings and to the following description relating thereto, the figures showing by way of non-restrictive examples, various means for carrying the invention into effect.

Figures 1 to 6 of the drawings represent diagrammatically the principle of the arrangement according to the invention; thus,

Figure 1 shows in vertical section a compariso element arranged within an aeroplane wing.

Figure 2 is a plan view of the aeroplane win shown in Fig. l and Figure 3 is a cross-sectional view thereof;

Figure 4 shows diagrammatically thearrangement of a servo-motor with its control and feed members;

Figure 4a illustrates a modification of the apparatus of Figure 4.

Figure 5 shows an arrangement wherein the comparison element is formed by two sections;

Figure 6 shows in section the connection between the comparison element and the mechanism displaced by the servo-motor.

Figure 6a'shows the arrangement of a connection between the lift varying means and a control surface of the aricraft.

Figures 7 to 14 represent a practical embodiment satisfying in its entirety the principles explained, adding thereto various improvements of detail important owing to their general extent; and of which Figure 7 is a vertical section,

Figure 8, a plan view,

Figure 9, a ide view,

Figure 10 is a plan view of the servo-motor and its accessory parts, and

Figures 11, 12 and 13 are side views thereof,

Figure 14 is a cross section, on a larger scale, of the arrangement shown in'Figure 10.

Figures 15 to 24 are diagrams showing the successive positions of the different members of the mechanism.

Referring more particularly to the drawings, Figure 1 shows the arrangement of a comparison element i in the interior of an aeroplane wing E; the outer extremity 2 of the comparison element is connected to the structure of the wing, while the inner extremity 3 of said-element extends into the interior of therfuselage 8 and is-connected to the control member of a servomotor by a a suitable means, such for example, as that shown in Figure 4.

Figur 2 represents a plan view of'the aeroplanewinglofFigure i. Thlswingcomprisesa 3 movable about a pivot I on the trailing edge of the wing and controlled by connecting rodsluchas |3alsoshowninI"isure3.whichis a cross-sectional view of the wins. The connecting rod I3 is hinged at its outer extremity II to thefiap 3 and at its other extremity l2 to one arm of a bell cranklever, which is mounted on a pivot 3 carried by the wing structure. The other arm l3 of the bell crank lever is coupled by a connecting rod It to one arm l3 of a second bell crank lever pivoted at I13 and which is connected at I! to the rod of the piston ll of a servo-motor cylinder l3.

Figure 4 shows atically and .on a larger scale an example of a servo-motor with its control and feed members. 7 The servo-motor is of the hydraulic type and comprises a cylinder l3 and a piston l3 dividing the cylinder into two spaces 33 and 36. For a given displacement of the piston l6, the space 36 alters less in volume than the space by reason of the volume of the space 33 occupied by the piston rod. The space 33 is in permanent communication by a pipe 60 with a hydraulic accumulator 31 in which a liquid is stored under the pressure of any elastic agent. The cylinder space 33,-through a pipe 33, communicates with a threeway cock 3|, which has a control plug operatively coupled by a lever 3|. Two other pipes 32 and 33 opening into the valve 3| serve to place the cylinder space 33 in communication with an external collecting tank 33 or with the accumulator 31 through the cock or valve. The tank 36 communicates with a pump 3|) or with a hand emergency pump 39, and with a pipe 32 which is provided with valves I32 capable of preventing the return of the oil from the accumulator towards the tank. The control by the lever 6| of the cock 3| is eflected by means of a connecting rod 36 hinged at one end of a rocker 2| which is connected at the other end 20 to an arm extending from the bell crank l6. The rocker 2| is connected at a point 22 by a connecting rod 24 to a system of amplifying levers 25, 26 and 26 interconnected among themselves by links 26 and 2:1 and hingedly connected at 3 to the comparison element I.

The operation of the device is as follows: under the effect of a gust of air or of the movement of the aeroplane when the longitudinal trim thereof is straightened out, the point 3 shifts and causes the displacement of the point 22 and a rotational movement of the plug of the cock 3| by means of the amplifying lever system, bringing the chamber 36 into communication with the accumulator 31. This causes a downward movement of the piston l3, and a movement of the point 26, the eflect of which, relatively to the lever 6| of the plug of the-cock 3| is opposite to the displacement of the point 22 as det rmi by the displacement of the point 3. The piston l3, in moving the bell crank l3, also moves the flap 6 so as to compensate for the intensified aerodynamical action of the gust of air or straightening out movement of the aeroplane. The gust or squall having passed or the straightening out movement having become less accentuated. the point 3 returns to its initial position and this efiects a reverse movement of the cock so as to cause the chamber 36 to be brought into communication with the tank 33.

The operation of pump 33 may be made automatic in dependence upon the pressures in the accumulator 31, while the object of said pump is to recharge the accumulator, and to limit the 2,986,130 v volumeofthellqlildinthetankll-incase anything happens to the mechanical control of pump 33, the manually operable eme Iency pump mounted on pivot's'll which are carried by the wing structure. .It is then suiiicient to connect oneortheendsofoneofthebarsltothepoint 23ofthebellcrank|3andanendoftheother bar to the lever 3| of the cock 3|. Hence, when it is desired to use the aforesaid mechanism not only as an automatic force limiting device but also as a manually actuated night controlling device, means may be provided for varying the length of the connecting rod 33 or 23 in Figure 4, the power necessary for actuating said means being only slight. while the power necessary for the deflection of the flap 3 for the purpose of fight control is furnished by the accumulator When it is desired that the wing deformation shall act on the position of the flaps differently than as a function of the variation speed of said wing deformation, an intermediate element may be introduced in the connection between the driving extremity of the comparison element and one of the points of the mechanism displaced by the servo-motor, said intermediate element being elastic with initial-tension and provided with damping means. I

Figure 6 shows a device forming one means of embodying a connection of this ype. interposed between the lever 32 of Figure 5 and the point 20 of the bell crank lever actuated by the servomotor. This device includes a spring 13 held between two washers 1| and 12, while a rod 13 extends between the two washers H and 12 and through the spring. Movement of the rod 13 upward is transmitted to the washer 12 by a ring 13 and downward to the washer II by a stop ring 13. The whole is enclosed in a cylindrical casing 13 having a cover ll which is hinged by a strap 13 to the point 23. A damper 13 connected between the lever 32 and a fixed point completes the device.

The invention has been described so far as applied to a half wins. but it is easily possible to generalize the application, thereof to the two wings of an aircraft either by a separate control for each wing or by a single control, the flaps of the two wingsin the latter case being connected together in an invariable manner.

The connection 33 (Figure 4) between the accumulator 31 and the cylinder space 36 which serves to return the piston l3, may be replaced by any elastic means for returning the piston, for example, springs exerting their action at any suitable point of the mechanical connections of the different members of this arrangement.

This embodiment is shown in Figure 4A, in which the connection is omitted and the cylinder 3 is open at the bottom, while an elastic cord I33, anchored to a fixed point of the system, is attached on the other hand to the arm II of the lever in order to exert on the piston l3 a force antagonistic to the liquid admitted to the Space 33.

The arrangements already described above are illustrated in Fig. 6A. wherein furthermore a connection is shown between the stabilizing flap 4 and the horizontal rudder BI. This connection is established across the various control rods. 90, 89, 85 and 00. An elastic connecting member 92 and a damper 03 are interposed in the connection 90. The horizontal control 90 may also be actuated independently, as usual, by the control member across the connection 81.

The following Figures 7 to 14 show a more detailed example of the invention in which the mechanism described is of the hydro-pneumatic type.

This embodiment of the invention will be better understood by the following description with particular reference to Figures 7 to 14 which connected by means of hell crank levers I01 and I08 and a coupling rod I08. The control lever I09 of the servo-motor is hinged at IIO to a connecting rod III which connects the lever I09 to the bell crank lever I08. A group of extensible springs II2 acts against the connecting rod III and tends to lower the flap G. Cords I, I which detect the deformation of the wing are arranged as a double system; one of the extremities of this prises a toothed sector I40 movable about a pivot system including the free ends of the cords I,

is anchored at II5 to a fixed point of the frame of the servo-motor IOI At the ends of the cords I, I remote from the servo-motor, the cords I and I are interconnected by a reversing mechanism comprising bell crank levers H6 and I" which are operatively connected together by a rod II8. This latter device is equivalent to a rocking lever counterbalancing the forces in and the displacements of the double cord system I and I'. The cords I are anchored at II9v to a movable lever I hinged at I2I on the frame of the servomotor.

In Figures 10, 11, 12 and 13 are shown the plan view and the diflerent side views of the servomotor. In the plan view of Figure 10 the arrangement of the accessory parts such as pumps, accumulator and tanks are shown diagrammatically with the servo-motor. The active piston of the servo-motor is shown in Figure 10 at I9 and the cylinder space in which the motive liquid acts on this piston is indicated at 35. The liquid under pressure comes from the accumulator, shown at 31, through a pipe 60 while the return of the liquid discharged from the space occurs through a pipe 32 into the tank shown diagrammatically at 38. The recharging oi the accumulator 31 is normally ensured by the automatically controlled pump shown diagrammatically at 40.

The manually operable safety or emergency pump '39 duplicates the pump and allows recharging the accumulator 31 from the liquid accumulated in the tank 38. The piston I9 which in the case shown is single acting from the left towards the right, bears on the lever I09 by means of a roller I30, the lever I09 being pivoted on the frame IN on a pivot I3I. The lever I09 is provided with a fixing device which coma spring controlled piston I42acting on its extremity I44. When pressure liquid from the accumulator 21 is not applied on the piston I42 through the pipe I19 controlled by a-valve III operated by the pilot so that the control spring of the piston may act freely on the said sector, the sector I44 can freely engage with a toothed plate I43 carried by the lever I09. The piston rod I 32 of the piston I9 is slotted so as to allow the lever I09 to extend-therethrough and the outer extremity of this rod actuates an oblique rocker I33 which is mounted at one end upon a fixed pivot I34 shown in Figures 10 and 11. The

rocker I33 at its other end I35 controls a driving member of a transmission device which introduces a demultiplication in the displacements of the driving and driven members, said demultiplication being variable with the driving member speed as well known in the art, and the fixed body I35 of which is best shown in Figure 12.

The member controlled by this mechanism shown at I31 in Figure 12,'carries a small rocking lever I 45, shown in Figure 14, which shows on a larger scale a section of the device of Figure 10. The member controlled by the device I35 shown in Figure 14 carries the small double rocker I45 and its extension is guided by a bearing I46. The double rocker I45 is connected at one end by means of a link I41 to a manipulating member I48. As shown in Figure 14 the member I49 comprises a screw-threaded spindle about which a nut I49 can rotate which is secured against lateral and longitudinal displacement. The nut I49,

the rotation of which may be efiected by the pilot, can be driven by chain, cable or by a flexible transmission with tangential engagement of the nut, as illustrated diagrammatically at I50 by a worm gear. I y

The type of manual control may be such that the pilot acts on both wings either so that moving flaps are displaced in the same direction when they are used as camber flaps, or in opposite direction if they are used as lateral flight control flaps. This part of the device being kfiown in the fleld'of current practice of flight control for aircraft is not here describedin greater detail.

The other end of the rocker I45 is pivoted at I5I to a connecting rod I52 which couples the rocker I45 to one end of a second rocking lever- I53 movable about a pivot I54 carried by the previously mentioned lever I20 so that the rocker I45 controls this second rocker.

The other end of the rocker I53 is connected by a rod I55 to a rocking lever I56 controlling valves I50 and I6I; the rocker I56 pivoted at I5'I carries two adjustable thrust members I58 and I59 respectively controlling the valves I 'ters the chamber I64 and I56 and keeps the volume occupied by the liquid approximately constant; therefore the stress of the liquid on the valve does not increase whatever the latters position of opening. The valves are under the influence of return springs I52 and I63 which normally press the valves on their seats. The valves I60 and I6I control the passage of the liquid respectively between chambers I64 and I66 on the one hand and I66 and I61 on the other hand. One of the chambers I64 or I66 communicates with the piping 60 and the other chamber communicates with the piping 32, while chambers I65 and I61 communicate with the space 35 forming the working chamber of the active piston I9.

Any other combination and communication can be effected provided that one of the valves controls the entry.of the liquid (piping 60) whilst the other controls the discharge of the liquid (piping 32).

The lever I20 on which the system of detecting cords I' acts through a joint H9 is connected in such manner as to oppose the action of these cords by means of a torsion bar or a rubber socket fixed on the axis I2 I. The lever I20 has a toothed part I10 at its free end adapted to engage with a movable section I1I pivoted at I12 to the fixed frame and controlled angularly by a rod I13 terminated by a piston I14 on which a return spring acts comprising a series of Belleville washers I16, and if necessary a fluid under pressure is also introduced on to the face I16 through a tube I16, which fluid may be taken from the accumulator 31. The admission of said fluid to the piston I14 is controlled by a valve I11 operable by the pilot, as has been mentioned in connection with piston I42. The devices I10--I1I and I40I43 serve to lock and to release the levers I20 and I03 respectively, the pilot doing this by hand.

The operation of the system will be easier to follow by reference to Figures 15, 16, 17, 18 and 19, which represent diagrammatically the successive positions occupied by the different members. The pilot member acts on the control I60 to produce the displacement of the flaps and then brings this control back to the initial position of rest. In Figure 15 the device is at rest. When the member I48 in Figure 14 has moved towards the right, the rocking lever I46 in Figure 16 takes up an inclined position, the lever I being assumed to be stationary and locked (by the toothed sector shown in Fig. 14) the rocking lever I63 in turn also takes up an inclined position and eflects the inclination of the rocking lever I66 and the opening of the admission or charging valve I60. This effects in a displacement of the piston I3 of Figure 17 which causes an angular movement of the control lever I03, which in turn effects the deflection of the flap and, by means of the rocking lever I33, the displacement of the member leading from the device I36. This then also causes the displacement of the actuated member I31 to occur, as well as a reverse movement of the rocking lever I46 transmitted to the rocking lever I63 and to the rocking lever I66, whereupon the valve I60 again closes, and Figure 17 thus represents a fresh position of equilibrium of the lever I03 and also of the flap resulting from the displacement of the pivot of member I46 and of the pivot I30 of lever.-I46.

Figures 18 and 19 represent the reverse movement when the member I43 is moved in the opposite or return direction and consequently when the pivot I60 is brought into the position of Figure 15. The system as a result of the open ing of the valve I6I -then resumes the same positions again, Figures 15 and 19 being identical.

Figures 20, 21, 22, 23 and 24 illustrate the operation of the device under the action of the detector of deformationof the wing alone, the pilot member I43 remaining stationary, Figure 20 corresponding to the rest position.

Under the action of a squall or of a trim straightening movement, the wing having been deflected, the cords I' shown in Figure 8 exert a tractive force on lever I20 and displace it into an inclined position; while as shown in Figure 21 the rocker lever I63 inclines and the valve I60 opens, in view'of the fact that the point I60 does not move. The result is the displacement of the lever I08 (Figure '22) which tends to raise the flap and thus to diminish the lift of the wing. The movement of the lever I 00 by means of the lever I33 and of the connecting member I36, displaces the point I6I which acts on the rocking lever I63 and consequently on the rocking lever I66, which closes the valve I60. The lift of the wing having diminished by virtue of the deflection of the flap and the squall having passed, the lever I20 tends to resume its initial position. As shown in Figure 23, a fresh displacement of the rocking lever I63 results which effects the opening of the valve I6I. The squall having passed, the system resumes its position of equilibrium. As shown in Figure 24, the deadening of the oscillations which might start by the coupling made between the deflection of the flap and the deformation of the wing, is obtained by the play of the connecting member I36. Owing to the presence of this connecting member, any

danger of vibration will be eliminated outside the possibility of damping proper of the wing on which the device for the limitation of the aerodynamic forces is mounted.

It has been stated that levers I03 and III are provided with looking devices including respectively the toothed sectors I40 and HI. The application of these sectors on to the corresponding parts I43 and I10 of the levers is effected by resetting springs I42 and I13, the action of which is equilibrated by the motive pressure of the fluid which is exerted in the accumulator. This pressure may be increased or reduced as desired by the pilot, by manipulation of a valve ill or I11. Whenever the pressure of the liquid drops owing to an accident the locking of the levers takes place automatically for the purpose of ensuring safety. To this end the adjustment;

of the springs I42 and I16 will preferably be come locked or immobilized, and this will eliminate the action of the detectors of wing deformation. The result will be that at the moment when the lever I03 in its turn is about to become locked while the pressure is continuing to fall in the accumulator, said lever I03 before being locked will have taken up the position corresponding to a condition of rest, 'as defined by theposition of the member I43 operable by the pilot.

The invention is naturally capable of numerous modifications of construction within the scope of the appended claims.

It should particularly be understood that the device may control any system of flaps with or without slots and more generally any member 2 element associated with the wins surface and 'two' active positions in which one of the said adapted to be altered in shape by the aerodynamic forces on the wing in a manner different from the alterations in shape of the wing surface and means comprising a servo-motor oper-v able to control by the comparison element the said lift varying means, the said servo-motor comprising a motive piston in a cylinder filled with fluid, a fluid reservoir under pressure and a fluid discharge reservoir connected respectively to the cylinder spaces on each side of the piston,

a distributing valvein the said connections controlled by the comparison element and a recharging pump interposed in the connection between the reservoir; under pressure and the dis:- charge reservoir. e

2. In a wingedaircraft, means operable to vary the lift of the wings, at least one comparison element associated withthe wing surface. and adapted to be altered in shape by the aerodynamic forces on the wing in 'a manner different from the alterations in shape of the wing surface and means comprising a servo-motor operable to control by the comparison element the said lift varying means, the said servo-motor comprising a. motive piston in a cylinder filled with fluid, a fluid reservoir under pressure and a fluid discharge reservoir connected respectively to the spaces of the cylinder on each side of. the piston, a distributing valve in the said connections controlled by the comparison element, an automatic recharging pump interposed in the connection between the reservoir under pressure and-the discharge reservoir and a manual pump forming a duplicate of the automatic'pump.

3. In a winged aircraft, means operable to vary the lift of the wings, at least one comparison element associated with the wing surface and adapted to be altered in shape by the aerodynamic forces on the wing in a manner different from the alterations in shape of the wing surface and means comprising a servo-motor operable to control by the comparison element the said lift varying means, the said servo-motor comprising a motive piston in a cylinder fllled with fluid, a fluid reservoir under pressure and a fluid discharge reservoir connected respectively to the spaces of the cylinder on each side of the piston, valves controlling respectively these connections, a rocking lever connectedv to the said valves, means controlled by the comparison elinent to place the rocking lever alternately in two active positions in which one of the said valves is opened and the other closed and into at least one intermediate neutral position in which the two valves are closed, and a re-charglog pump interposed in the connection between the reservoir under pressureand the discharge reservoir.

4. In a wingedaircraft, means operable to vary the lift of the wings, at least one'comparison element associated with the wing-surface and adapted to alter in shape by the aerodynamic forces on the wing in a manner different from the alterations in shape of the wing surface v and means comprising .a servo-motor operable to control by the comparison element the saidlift.

varying means, the said servo-motor comprising a motive piston in a cylinder filled with fluid, a fluid reservoir under pressure and a fluid discharge reservoir connected respectively to the spaces ofthe cylinder on each side of thepiston, valves controlling respectively the said connections, a rocking lever. connected to-thesaid valves, means controlled by the comparison element to place the rocking levers alternately-in valves is open and the other closed and into at least one intermediate neutral position in which both valves are closed, means operable to control the rocking lever by the movements of the piston of the servo-motor, means operable to control the rocking lever by a manipulating member controllable by the pilot of the aircraft, and a recharging pump interposed in the connection between the reservoir under pressure and the discharge reservoir.

5. In a winged aircraft, means operable to vary the lift'of the wings, at least one comparison element associated with the wing surface and adapted to be altered in shape by the aerodynamic forces on the wing in a manner different from the alterations in shape of the wing surface and means comprising a servo-motor operable to control by the comparison element l the said lift varying means, the said servo-motor comprising a motive pistonin a cylinder fllled with fluid, a fluid reservoir under pressure and a fluid discharge reservoir connected respectively to the spaces of the cylinder on each side of the piston, valves controlling respectively the said connections, a rocking lever connected to these valves, means controlled by the comparison element to place the rocking lever alternately into two active positions in which one of the said valves is opened and the other closed and into at least one intermediate neutral position in which the two valves are closed, means operable to control the rocking lever by the movements of the piston of the servo-motor, means operable to control the rocking lever by a manipulating member controllable by the pilot of the aircraft, means operable to suppress the actionof the comparison element on the rocking lever, and a recharging pump interposed in the connection between the reservoir under pressure and the discharge reservoir.

6. In a winged aircraft, means operable to vary the lift of the wings, at least one comparison element associated with the wing surface and adapted to be altered inshape by the aerodynamic forces on the-wingin a manner different from the alterations in shape of the wing surface and means comprising a servo-motor operable to control by the comparison element the said lift varying means, the said servo-motor comprising a motive piston in a cylinder fllled with fluid, a fluid-supply .reservoir'under pressure and a fluid discharge reservoir connected I operable to control the rocking lever by the movement. of the piston of the servo-motor,

- means operable to control the rocking lever by a manipulating member controllable by the pilot of the aircraft, means operable in response to a predetermined pressure value in the supply reservoir of the servo-motor to suppress auto- 1 matically the action of the comparison element ,on the rocking lever, and a recharging pump interp'osed in the connection between the reservoir under pressure and the discharge reservoir,

.7. In a winged aircraft, means operable to vary the lift of the wings, at least one comparison element associated with the wing surface and adapted to be altered in shape by the aerodynamic forces on the wings in a manner different from the alterations in shape of the wing surface, means operable to control by the comparison element the said lift varying means,v and means operable to control the inter connections means operable to vary the lift'of the wings, a control surface means operable tore-establhh the longitudinal trim of the craft when the wines have been deflected, at least one comparison element pivotally associated with thawing surface, means upon the corresponding wing causing said comparison elements-"to be altereiin shape by the effect of the aerodynamic forces acting to deform the shape of the wing in a manner contrasting with the deformation of said wing, operable means for controlling said lift varying means through said comparison element. elastic connecting means serving to connect the lift varying means with the control surface means, and means imparting initial tension and damping to said elastic means.

PIERRE ERNEST mama. 

